Hi @Katiejackson41 ,
Hi @Katiejackson41 ,
There is an app called Zipprover, which exactly solves your problem.
https://apps.shopify.com/shipping-availability-checker
It will ask for delivery area zipcode and if the zipcode is not deliverable then it can restrict the add to cart and additionally collect email from the customer as wait listing, so as a store owner you can inform them when you open service in their area. Save lot of support debts/time for you and your customers.
Please let me know if it solves your issue or you need any help with that.
P.S We are the author of that app.
Best of luck for your store 